JP2001145329A - Eddy current reducer - Google Patents

Abstract

(57) [Object] To provide an eddy current reduction device that eliminates a problem due to thermal expansion by rotatably supporting a steel magnet support cylinder on an aluminum inner cylinder part. SOLUTION: An immovable guide cylinder 10 made of aluminum is disposed inside a brake drum 7 connected to a rotating shaft. A large number of magnets 24, 24A are inserted into the inner space of the guide tube 10 having a rectangular cross section.
Support cylinders 14, 1 made of steel and connected at equal intervals in the circumferential direction
4A is rotatably supported, and the other is non-rotatably supported. Guide cylinder 1 facing inner peripheral surface 7b of brake drum 7
The ferromagnetic member 15 facing each of the magnets 24, 24A is coupled to the outer cylinder portion 10a. Switching between non-braking and braking is performed by rotating the magnet support cylinder 14 forward and backward. The magnet support tube 14 is moved by the bush 12 to the inner tube portion 10A of the guide tube 10.
And a steel sleeve 61 is connected to the outer peripheral surface of the inner cylindrical portion 10A facing the bush 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to an eddy current reduction device mounted on a large vehicle for assisting a friction brake, and more particularly, to a stationary guide cylinder made of a non-magnetic material such as aluminum and a magnetic material such as steel. The present invention relates to an eddy current reduction device in which a magnet support cylinder is stably rotatably supported even when it receives eddy current heat.

[0002]

2. Description of the Related Art As disclosed in, for example, Japanese Patent Publication No. 6-81487, a guide cylinder having a rectangular hollow section made of a non-magnetic material is disposed inside a brake drum, and the guide cylinder has an inner space. At least two magnet support cylinders having a large number of magnets whose polarities with respect to the inner peripheral surface of the brake drum are alternately changed in the circumferential direction are accommodated in the portion, and one magnet support cylinder is rotated forward and backward by an arrangement pitch of magnets. As a result, the eddy current deceleration switches between a braking position in which magnets of the same polarity arranged in the axial direction face the ferromagnetic plate coupled to the outer cylinder portion of the guide cylinder, and a non-braking position in which magnets of different polarities face each other. In the apparatus, the outer cylinder and the inner cylinder of the guide cylinder are cast from a non-magnetic material such as aluminum, and a large number of ferromagnetic plates are cast in the outer cylinder at equal intervals in the circumferential direction.

The inner peripheral surface of a bush (drive hash) press-fitted into the inner peripheral surface of the magnet support cylinder is supported on the outer peripheral surface of the inner cylinder portion of the guide cylinder. In general, a guide cylinder made of aluminum for weight reduction has an alumite treatment on the surface of the guide cylinder so that a sliding portion of the magnet support cylinder does not wear. On the other hand, the magnet support cylinder into which the bushing is press-fitted is made of soft magnetic or magnetic steel, and the ambient temperature reaches 900 ° C in the braking state of the eddy current reduction device. The gap between the bush and the sliding portion of the guide tube was reduced due to the difference in the thermal expansion coefficient (aluminum has a thermal expansion coefficient about twice that of steel), resulting in malfunction and wear of the bush. Further, since the thermal conductivity of the alumite layer on the surface of the guide cylinder is as low as 1/10 of that of aluminum, dissipation of frictional heat is suppressed, and the temperature of the surface of the guide cylinder increases.

[0004]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, an object of the present invention is to solve the problem caused by thermal expansion caused by rotatably supporting a steel magnet support cylinder on an aluminum inner cylinder. An eddy current reduction device is provided.

[0005]

In order to solve the above-mentioned problems, according to the structure of the present invention, an immovable guide cylinder made of a non-magnetic material such as aluminum is disposed inside a brake drum connected to a rotating shaft. At least two magnet support cylinders made of a magnetic material such as steel, in which a large number of magnets are connected at equal intervals in the circumferential direction, are rotatably supported, and the other is non-rotatably supported in the inner space of the guide cylinder having a rectangular cross section. The outer cylinder portion of the guide cylinder facing the inner peripheral surface of the braking drum has a portion facing the magnet made of a ferromagnetic material. In the eddy current reduction device that switches between braking and the braking position and generates a braking force based on an eddy current on the braking drum by a magnetic field that passes through the ferromagnetic material from the magnet at the braking position, one of the magnet support cylinders is bushed. Inner tube part of guide tube Supporting, characterized in that combining the steel sleeve on the outer circumferential surface facing the bushing of the inner cylinder portion.

Further, according to the structure of the present invention, an immovable guide cylinder made of a non-magnetic material such as aluminum is disposed inside a braking drum connected to a rotary shaft, and a large number of guide cylinders are inserted into an inner space having a rectangular cross section of the guide cylinder. Rotatably supports a magnet support cylinder made of a magnetic material such as steel in which the magnets are connected at equal intervals in the circumferential direction, and faces the magnet at an outer cylinder portion of the guide cylinder facing the inner peripheral surface of the braking drum. The portion is made of a ferromagnetic material, and switching between non-braking and braking is performed by rotating the magnet support cylinder forward and backward. At the braking position, a control based on an eddy current is performed by a magnetic field transmitted from the magnet to the ferromagnetic material. In an eddy current reduction device that generates power on the braking drum, the magnet support tube is supported by a bush on an inner tube portion of the guide tube, and a steel sleeve is provided on an outer peripheral surface of the inner tube portion facing the bush. Characterized by being combined That.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, the alumite treatment of a guide cylinder rotatably supporting a bush connected to a magnet support cylinder is eliminated, and a steel sleeve is press-fitted or cast into the guide cylinder. In addition, the difference in the coefficient of thermal expansion between the guide cylinder and the magnet support cylinder is reduced to prevent malfunction and abrasion of the bush. The surface of the steel sleeve connected to the guide tube is smoothed. The sleeve may be only a portion supporting the movable magnet support tube, or may be extended to a portion supporting the immovable magnet support tube.

[0008] By connecting a steel sleeve to the outer peripheral surface of the aluminum inner cylinder portion facing the steel magnet support cylinder by externally fitting or press-fitting the same, heat generated by eddy current heat during braking is obtained. The expansion prevents the gap between the rotary sliding portions from being reduced, thereby ensuring smooth forward and reverse rotation of the magnet support cylinder. In addition, the alumite layer at the portion facing the magnet support cylinder is eliminated by the connection of the steel sleeve, whereby the temperature rise of the sliding surface can be reduced.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An eddy current reduction device according to the present invention is, for example, a brake drum 7 made of a conductor connected to an output rotation shaft of a vehicle transmission, and a guide made of a non-magnetic material disposed inside the brake drum 7. The guide tube 10 includes a movable magnet support tube 14 and an immovable magnet support tube 14A that are accommodated in the inner space of the guide tube 10 having a rectangular cross section. The braking drum 7 has the flange 5a of the boss 5 superimposed on the mounting flange 2 having the spline hole 1 fitted on the rotating shaft, and is fastened with a plurality of bolts and nuts (not shown). A universal joint for connecting the propulsion shaft to the rotating shaft is connected to the mounting flange 2 shown by a bolt 4, and the boss 5 is connected to another bolt other than the bolt 4.
Are connected. The base end of a braking drum 7 provided with a cooling fin 7a is connected to the distal ends of a large number of support arms 6 extending radially from the boss 5. The base shaft portion 6 of the support arm 6 allows the brake drum 7 to expand and expand due to eddy current heat.
a is fitted into the shaft hole 8 of the boss 5, and a spring 9 is interposed between the bottom of the shaft hole 8 and the shaft portion 6a.

The guide tube 10 has an outer tube portion 10a and an inner tube portion 10b.
The left end wall and the right end wall 11b are joined to both ends to form an inner space having a rectangular cross section. The movable magnet support tube 14 made of a magnetic material is provided in the inner space of the guide tube 10 and is supported by the bush 12 on the inner tube portion 10b so as to be capable of rotating forward and backward. A groove-shaped support plate 1 that projects axially from the magnet support tube 14 and has a grooved cross section.
The roller 57 is supported by 6. The roller 57 is engaged with a groove 65 provided on an end side surface of the rod 56 of the actuator. The magnet support tube 14 has a magnet 24 on the outer peripheral surface facing the left half of each of the ferromagnetic members 15 of the outer tube portion 10a.
5 are connected in such a manner that the polarities for 5 are alternately different in the circumferential direction. The stationary magnet support tube 14A made of a magnetic material is the guide tube 1
0, and is supported by the inner cylindrical portion 10b and fixed to the end wall 11b by pins 53. A magnet 24A on the outer peripheral surface of the inner cylindrical portion 10b facing the right half of each ferromagnetic material portion 15
Are connected so that the polarity with respect to the ferromagnetic body part 15 is alternately different in the circumferential direction.

FIG. 1 shows the connection between the end of the rod 56 of the actuator and the roller 57 of the support plate 16 connected to the end wall of the magnet support tube 14. The end wall 11a joined to the left end of the outer tube 10a and the inner tube 10b to cover the connection between them is omitted, and the outer wall 54 extending from the outer tube 10a and the inner wall 60 extending from the inner tube 10b are removed. End of the cover plate 55
Are closed by a plurality of bolts 59. The bolt 58 couples the end wall 11a, the outer cylinder part 10a, and the ferromagnetic body part 15. Although not shown, the actuator has a piston inserted into a cylinder, oil chambers are defined at both ends, and a roller 57 is engaged with a surface of the end of a rod 56 protruding from the piston to the outside and facing the support plate 16. A groove 65 is formed.
The support plate 16 is in contact with the right side surface of the rod 56 so as to cover the groove 65. The inner cylinder portion 10b has a wall plate 62 projecting radially inward to the end of the case 40 of the gear transmission by stud bolts 64 and nuts 63.

As shown in FIG. 2, the magnet 24A of the magnet support tube 14A has a cylindrical surface on the inner surface and the outer surface, and a non-magnetic material is inserted between the step portions 35 formed at the circumferential ends of the magnets 24A. A fixing bracket 31 made of a body and having a T-shaped cross section is engaged, and is fastened to the magnet support cylinder 14A by a bolt 32. Magnet 2
4 is similarly connected to the magnet support tube 14.

According to the present invention, the movable magnet support tube 14 is provided in order to eliminate the problem of thermal expansion caused by rotatably supporting the steel magnet support tube 14 on the aluminum inner tube portion 10b. Is the inner cylindrical portion 10b by the bushing 12.
And a steel sleeve 61 is coupled to the outer peripheral surface of the inner cylindrical portion 10b facing the bush 12. Specifically, a steel sleeve 61 is cast on the outer peripheral surface of the aluminum inner cylinder portion 10b facing the steel magnet support cylinder 14, or the inner cylinder portion 10b is pressed into the sleeve 61. Join. When the inner cylinder portion 10b is press-fitted into the sleeve 61, the outer diameter of the inner cylinder portion 10b is reduced by the thickness of the sleeve 61 in advance.

When the brake is not applied, as shown in FIG. 1, the magnet 24 of the magnet support tube 14 and the magnet 24A of the magnet support tube 14A are
The polarities facing the ferromagnetic body portion 15 are opposite to each other. At this time, the magnets 24 and 24A form a short-circuited magnetic circuit w between each ferromagnetic body portion 15 and the magnet support cylinders 14 and 14A, and do not apply a magnetic field to the braking drum 7. During braking, the actuator moves the magnet support tube 14 from the non-braking position as shown in FIG.
When the magnet 24 is rotated by the pitch of the arrangement of the magnets 24 to the braking position shown in FIG.
And the magnetic field is applied to the braking drum 7 via the ferromagnetic portion 15. When the rotating brake drum 7 crosses the magnetic field, an eddy current flows through the brake drum 7, and the brake drum 7 generates a braking torque. At this time, each magnet 24, 2
4A forms a magnetic circuit z between the braking drum 7 and the magnet support cylinders 14 and 14A.

As shown in FIGS. 3 and 4, according to the present invention, a single steel magnet is inserted into the inner space of an aluminum guide tube 10 in which a large number of ferromagnetic members 15 are cast at equal intervals in the circumferential direction. Support tube 1
4 are rotatably accommodated, and two magnets 24 are arranged on the outer peripheral surface of the magnet support tube 14 so as to oppose each ferromagnetic member 15 by two, and the two magnets 24 have different polarities to the ferromagnetic member 15 in the circumferential direction. The present invention can also be applied to an eddy current reduction device having such a combination. At the time of non-braking, as shown in FIG. 3, when two magnets 24 having different polarities face each ferromagnetic body portion 15, a short-circuit magnetic circuit w is formed between the ferromagnetic body portion 15 and the magnet support tube 14. It is formed and does not exert a magnetic field on the braking drum 7. At the time of braking, magnet support cylinder 1
When the magnet 4 is rotated by the pitch of the arrangement of the magnets 24, as shown in FIG.
At this time, a magnetic circuit z is formed between the braking drum 7 and the magnet support tube 14. When the rotating brake drum 7 crosses the magnetic field, a braking torque based on the eddy current is generated in the brake drum 7. Also, instead of casting a ferromagnetic material into an aluminum guide tube, the guide tube is made of ferromagnetic ferrite stainless steel, and a non-magnetic portion is generated by heat treatment to obtain the same effect as described above. You may.

[0016]

As described above, according to the present invention, an immovable guide cylinder made of a non-magnetic material such as aluminum is disposed inside a brake drum connected to a rotating shaft, and the guide cylinder has an inner space having a rectangular cross section. At least one of the at least two magnet support cylinders made of a magnetic material such as steel in which a large number of magnets are connected at equal intervals in the circumferential direction is rotatably supported, and the other is non-rotatably supported. In the eddy current reduction device that switches between non-braking and braking by reverse rotation and generates a braking force based on eddy current in the braking drum by a magnetic field from the magnet at the braking position, one of the magnet support cylinders Is supported by the bushing on the inner cylinder portion of the guide cylinder, and a steel sleeve is connected to the outer peripheral surface of the inner cylinder portion facing the bushing. The clearance between moving parts is reduced Eliminating from that, smooth forward and reverse rotation of the magnet support tube is secured.

[Brief description of the drawings]

FIG. 1 is a front sectional view of an eddy current reduction device according to the present invention.

FIG. 2 is a side sectional view of the eddy current reduction device.

FIG. 3 is a front sectional view of an eddy current reduction device according to a modified embodiment of the present invention.

FIG. 4 is a side sectional view of the eddy current reduction device.

[Explanation of symbols]

2: Mounting flange 5: Boss 6: Support arm 6a: Shaft 7: Brake drum 7a: Cooling fin 8: Shaft hole 1
0: guide cylinder 10a: outer cylinder part 10b: inner cylinder part 11
a: End wall 11b: End wall 12: Bush 14: Magnet support cylinder 14A: Magnet support cylinder 15: Ferromagnetic body part 1
6: Support plate 24: Magnet 24A: Magnet 31: Fixing bracket 40: Case 53: Pin 54: Outer wall 55: Cover plate 56: Rod 57: Roller 60: Inner wall 61: Sleeve 62: Wall plate 65: Groove

Claims (4)

[Claims] An immovable guide cylinder made of a non-magnetic material such as aluminum is provided inside a brake drum connected to a rotating shaft, and a large number of magnets are circumferentially inserted into an inner space of a rectangular cross section of the guide cylinder. One of at least two magnet support cylinders made of a magnetic material such as steel coupled at equal intervals is rotatably supported, and the other is non-rotatably supported, and is provided outside the guide cylinder facing the inner peripheral surface of the braking drum. The portion of the cylinder portion facing the magnet is made of a ferromagnetic material, and one of the magnet support cylinders is rotated forward and reverse to switch between non-braking and braking. In the eddy current reduction device for generating a braking force based on eddy current on the braking drum by a magnetic field that passes through the magnet, one magnet support cylinder is supported by a bush on the inner cylinder portion of the guide cylinder, and the bushing of the inner cylinder portion is Made of steel on the outer peripheral surface facing Eddy current reduction apparatus characterized by having attached sleeve. 2. An immovable guide cylinder made of a non-magnetic material such as aluminum is disposed inside a brake drum connected to a rotating shaft, and a large number of magnets are circumferentially inserted into an inner space of a rectangular cross section of the guide cylinder. A magnet support cylinder made of a magnetic material such as steel coupled at equal intervals is rotatably supported, and a portion of the outer cylinder portion of the guide cylinder facing the inner peripheral surface of the braking drum and a portion facing the magnet is a ferromagnetic material. The material is used to switch between non-braking and braking by rotating the magnet support cylinder forward and backward, and a braking force based on an eddy current is applied to the braking drum by a magnetic field transmitted from the magnet to the ferromagnetic material at the braking position. In the eddy current reduction device, the magnet support cylinder is supported on the inner cylinder of the guide cylinder by a bush, and a steel sleeve is connected to an outer peripheral surface of the inner cylinder facing the bush. Eddy current reduction device. 3. The eddy current reduction device according to claim 1, wherein the steel sleeve is cast on an outer peripheral surface of the inner cylindrical portion of the guide cylinder facing the bush. 4. The eddy current reduction device according to claim 1, wherein an outer peripheral surface of the inner cylindrical portion of the guide cylinder facing the bush is press-fitted into the steel sleeve.